Automobile brake



Dec. 30, 1941. w. s. SACHER AUTOMOBILE BRAKE Filed Dec. 1, 1959 2Sheets-Shea? 1 W. S. SACHER AUTOMOBILE BRAKE Dec. 30, 1941.

2 Sheets-Sheet 2 Filed Dec. 1, 1939 Aid/V0144 4 01 5 94750 i 84 5504V194 V5 Patented Dec. 30, 1941 UNITED STATES PATENT OFFICE AUTOMOBILEBRAKE I William S. Sacher, Pottstwn,.Pa., assignor of. one-fourth toIsaac C. shalkop Philadelphia,

Pa., one-fourth to Earl I. Keiser, Pottstown, Pa., and one-fourth toFred B. Seeberger,

Yeadon, Pa.

I Application December 1, 1939, Serial No. 07,010

3 Claims. (01. 188-795) This invention relates to automobile brakes ofthe hydraulic type, and particularly to means for automaticallyadjusting such brakes.

The object of this invention is to provide a simple eificient meanswhereby hydraulic automobile brakes'may be automatically andsimultaneously adjusted to maintain proper frictional relation betweenthe brake drum and the brake band.

Another object of this invention is the provision of manually operatedmeans at a single point of control for the simultaneous automaticadjustment of hydraulic automobile brakes.

Another object of this invention is the provision of a manuallycontrolled automatic brake compensating means'that is' inoperative whenthe automobile engine is heated to driving temperature.

A further object of this invention is the provision of a signal means incombination with the hydraulic means controlling a hydraulic brakemechanism to indicate the need for brake adjustment. These and otherobjects and advantages will be readily apparent to those skilled in theart. a

The improvement claimed is hereinafter fully described. In theaccompanying drawings,

Figure 1 is an elevation, partly in section, showing a brake mechanismembodying the features of the invention, and

Figure 2 is a fragmental View of the brake mechanism partly in sectionshowing the detail of the invention, and

Figure 3 is a view taken on line a-a in Fig. 2, and

Figure 4 is a schematic view of an automobile showing the means foroperating the automatic brake compensating mechanism.

The reference characters indicate the same parts in the severaldrawings.

In the practice of the invention the conventional backing plate I hasthe usual brake shoes 2 mounted on the adjustable eccentric studs 3which are disposed in the backing plate I to secure the brake shoes inan articulating position at the lower ends thereof, the upper end ofsaid brake shoes being disposed in seating members in the hydraulicpistons in the cylinder 4. Details of the hydraulic cylinder and pistonsare not shown as they are well known standard equipment.

As both brake shoes are identically equipped with adjustment means, thedescription applies to both sides, one being a right hand ac ion. andthe other left hand.

A flat spring steel member 5 is mounted adjacent the center leg of the Tshaped brake shoe member 2, on the arcuate under face of said brake shoeon the side facing the backing plate I. This spring member is shaped topermit a centrally disposed rivet or screw 51:. to hold same rigidly tosaid shoe, the lower end of the spring following the arc of the brakeshoe, and the top end resting on the tip of said spring to form thechord of an arc the segmental height of which shall be approximately.010 of an inch or any predetermined height desired, and the center ofthe chord shall be in direct line with the center of the cam adjustmentmeans.

The automatic compensating means consists of a base member 6articulatedly fastened to the backing plate I by means of a screw orbolt 1 at the lower end thereof. A cam 8 mounted upon a-sleeve 9 havingratchet teeth it), forms an integral unit which is rotatably held inposition upon the upper end of the base member 6 by a headed bolt memberll passing therethrough, and through a slotted opening I2 in the backingplate I to which it is held in the desired position by a nut l l-a. SeeFigs. 2, and 3.

The bolt H has a recessed portion l3 into which a torsional spring l4 isfastened at one end through a. hole Hi, the other end of said spring l4engaging an opening IS in the sleeve member 9, the torsional action ofsaid spring upon being wound causes the cam sleeve 9 to rotate upon thebolt ll. The cam rise is developed to allow a maximum compensationequivalent to the thickness of the brake lining ll upon the brake shoes2.

A vacuum cylinder H3 is rigidly secured by angle plate member l9 to thebase member 6 and has a pawl member mounted in the head |8a of saidcylinder H3. The pawl 20 has a threaded member 2| to which is rigidlysecured an elastic diaphragm member 22 by means of a nut 23. The elasticdiaphragm 22 is held in operative position to the cylinder head l8a bythe cylinder 18. A spring 24 within the cylinder [8 holds the pawl 20 inoperative relation with the ratchet teeth It on the sleeve 9.

Suitable copper tubing 25a having about 5%" inside diameter is securedto the cylinder l8 by means of a nut 25, and both right and left handcylinder tubes are joined to a T member 251) as shown in dotted lines inFigure 1.

Operation In practice the device is operated as follows: the schematicdiagram, Fig, 4, shows an automobile engine 21, and an intake manifold28 which is suitably tapped for the vacuum line 29. This vacuum line 29joins the line 30 which enters into the engine water jacket and has atits end a thermostatically controlled bleeder valve 30-a that breaks thevacuum when the engine has heated to a predetermined temperature lessthan the maximum operating temperature. Various types of thermostats inuse in automobile engines which are adapted to become opened when theengine is hot, and to close when the engine is cold, may be used tocontrol the operation of valve 30a. A line 3! leads from the line 30 tothe dash inside the automobile and has a manually controlled valve 32which may be closed. The valve 32 is of a type that is normally adaptedto leave the end of the line 3| open to the atmosphere when retracted,and to .close said end to the atmosphere when pushed inwardly. From theline 30 there extends lines 33 to the front wheel brakes, and from lines33 there extends lines 34 to the rear wheel brakes, all the lines form-.ing an unbroken vacuum line between the brake compensating controlcylinders and the intake manifold, 28.

A switch 35 such as the conventionalstop light switch, is actuated by anadjustable operating member 36 mounted on the piston rod 31 to themaster hydraulic cylinder 38 which controls the hydraulic brakes. Whenthe brake bands have worn to a point where more than the requiredclearance of .010 of an inch between the brake lining l1 and the brakedrum 39 exists, it will be found that the piston rod 31 in the mastercylinder 38 travels a greater distance, thereby causing the switchoperating member 36 to close the sw'itch35 which lights a bulb 40mounted on .the dash to caution the driver of the need for brakeadjustment. The brakes cannot be adjusted until the engine cools and thethermostatic bleeder valve in the vacuum line has closed.

After the engine has become cold and the brake drums are likewise cold,the operator starts the engine, puts his foot down on the brake andimmediately closes the manual vacuum control valve 32 on the dash of thecar. The vacuum suction to each brake compensating cylinder retracts allthe pawls simultaneously thereby allowing the spring actuated cams tomove forward the required amount to contact the springs 5 opposite eachcam. These springs are sufficiently resistant to the spring actuated camsleeve springs to prevent depression of said springs 5. Releasing themanually operated valve 32 immediately bleeds the vacuum line and allowsall the pawls to return to operative engagement with the ratchet teethon the cam sleeves. Each tooth is spaced to allow an adjustment of .005of an inch of cam rise. The large spring 4| which retracts the brakeshoes 2 has sufficient power to depress the chordal height of the arebetween the spring 5 and the arc of the brake shoe 2 to allow therequired .010 of an inch clearance between the brake shoe 2 and thebrake drum 39 to prevent drag or frictional contact between the shoesand the drum.

It is obvious from the foregoing description that accidental adjustmentof the brake shoes cannot be effected while the automobile is inoperation. The engine must be cooled below the average operatingtemperature to permit the thermostatically controlled bleeder valve inthe vacuum line to close, thereafter the manually controlled valve tooperate the compensating means will become operative.

What is claimed as the invention and desired to be secured by LettersPatent, is:

1. In a brake mechanism of the character described, automaticallyadjustable stops for retractable brake shoes comprising; spring actuatedadjustable stop members, pawl and ratchet means to secure the stopmembers in adjusted position, a vacuum controlled diaphragm means toactuate the pawl, a vacuum means, and manually operated means forcontrolling the vacuum.

2. In a brake mechanism of the character described, automaticallyadjustable stop members forretractable brake shoes comprising;adjustable stop members, spring members to actuate the stop members,ratchet and pawl means to secure the stop members in adjusted position,a vacuum controlled diaphragm means to actuate the pawl, a vacuum linefrom the automobile engine to the diaphragm means, and manually operatedmeans for controlling the vacuum.

3. In a brake mechanism of the character described in claim 2, and aflat spring member secured to the inner face of the retractable brakeshoe and having a predetermined clearance therebetween, said springbeing interposed between the brake shoe and the adjustable brake stop.

WILLIAM S. SACHER.

